Study finds two types of colon polyps can raise bowel cancer risk fivefold

Bowel cancer, also known as colorectal cancer, is a major health concern. In Australia it ranks as the second leading cause of cancer death and the fourth most frequently diagnosed cancer.

Many colorectal cancers begin as polyps, which are growths that develop on the inner lining of the bowel. These growths are usually benign and cause no immediate harm. However, two specific types of polyps, — adenomas and serrated polyps — have the potential to develop into cancer over time.

Colonoscopy Study Reveals Fivefold Increase in Risk

To better understand this risk, researchers reviewed more than 8,400 colonoscopy records. The analysis showed that people who had both adenomas and serrated polyps faced a much higher likelihood of developing advanced precancerous changes. In fact, the risk was up to five times greater compared with people who had only one type of polyp.

“Polyps are common and usually harmless, but when both types appear together — what we call synchronous lesions — the risk of serious bowel disease or cancer rises sharply,” says Dr. Molla Wassie, lead author and researcher at the FHMRI Bowel Health Service.

The researchers also found that this combination may be more widespread than previously believed. Nearly half of patients who had serrated polyps were also found to have adenomas.

Separate Cancer Pathways May Occur at the Same Time

“This is one of the largest studies of its kind,” says Dr. Wassie.

“Our findings support growing international evidence that these two types of polyps may represent separate cancer pathways that can be active at the same time — making early detection and regular monitoring even more important.”

The study also suggests that serrated polyps may develop into cancer more quickly than adenomas. This highlights the importance of screening strategies and follow up colonoscopy schedules that reflect differences between polyp types.

Why Regular Colonoscopy Screening Matters

“Polyps become more common as we age, but the key is catching and removing them early,” says Dr. Wassie.

“If you’ve had both types of polyps, it’s especially important to stay on top of your colonoscopy schedule.”

People over age 45 or those with a family history of bowel disease are encouraged to speak with their GP or visit the National Bowel Cancer Screening Program to learn about available screening options.

The Southern Cooperative Program for the Prevention of Colorectal Cancer program (SCOOP) was first funded by the National Demonstration Hospitals Program Phase 3. Dr. Wassie is supported by a NHMRC Investigator Grant (#2009050).